Transcatheter arterial embolization has recently been recognized as an effective method for treating liver cancer and breast cancer. According to this method, one end of a catheter is inserted into a nutrient artery leading to the cancer or tumoral tissue and a material that occludes the nutrient artery is injected through the other end of the catheter to stop the blood flow. This necroses the cancer or tumor tissue since it is not supplied with additional nutrient. Commonly assigned Japanese Patent Application (OPI) Nos. 135214/79 and 58163/80 (the symbol OPI as used herein means an unexamined published Japanese patent application) and U.S. Pat. No. 4,265,233 proposed materials for wound protection and healing that have blood coagulation Factor XIII and thrombin fixed thereto. It has been reported (as in the 18th Conference of Japanese Society for Artificial Organs and Tissues) that these materials are effectively used as occluding materials in transcatheter arterial embolization. But one great disadvantage of the transcatheter arterial embolization technique is that it cannot be supplemented with chemotherapy which is another effective way to treat cancers or tumors. After transcatheter arterial embolization, administering an anti-tumor agent orally or by injection is meaningless since the nutrient artery has been closed to prevent the agent from reaching the cancer or tumoral tissue. Therefore, if transcatheter arterial embolization is effected, the surgeon either abandons chemotherapy or occludes the nutrient artery after injecting an anti-cancer agent through a catheter inserted into the artery. But this two-step method is not very effective since the applied anti-cancer agent runs away in an extremely short time to sites other than the target cancer or tumor tissue; for one thing, the agent is usually administered in solution and its amount is not very great, and for another, the nutrient artery has not been completed occluded. Therefore, the incompatibility with chemotherapy, the biggest problem with the transcatheter arterial embolization technique, is yet to be solved, and a new pharmaceutical preparation that is free from this defect is in great demand.
There is another technique that is considered to be promising as a method of treating cancer, and this is needle therapy. The term needle therapy as conventionally used means drawing body fluids through a hollow needle, but needle therapy as used hereunder relates to a method of examining and treating cancer or tumor tissue. Examination by needle therapy is generally referred to as biopsy and consists of examining a sample of body tissues. For application to the examination of cancer or tumor tissues, this technique consists of collecting a doubtful tissue with a needle and subjecting it to diagnostic examination. Two problems have been pointed out in connection with this technique. One is that the cancer or tumor tissue collected on the tip of the needle may contaminate normal tissue as the needle is withdrawn, and no effective method is available for avoiding this trouble. The other problem is bleeding. Unlike transcatheter arterial embolization wherein a catheter is inserted into a blood vessel, needle therapy involves piercing the body with a needle to reach the target tissue and causes bleeding from the damaged site. If the damaged site is normal, bleeding stops spontaneously and the damaged blood vessel is repaired in a fairly short period and there will be no adverse postoperative effect. But the cancer or tumoral tissue lacks ability to stop bleeding and repair a damaged blood vessel, and this is usually so with the neighboring tissues. Therefore, they have a great tendency to bleed during needle therapy and once they bleed, it is difficult to stop the bleeding. If serious bleeding is expected, the very operation by needle therapy must be abandoned. The problem of bleeding is particularly great with a spleen, which is rarely subjected to needle therapy. In most cases of needle therapy, the needle with the target tissue on its tip is withdrawn while a proper method is being applied to stop bleeding. The common method of achieving this object is to inject an aqueous solution of thrombin during the withdrawing of the needle. But even this method is not completely satisfactory since the ability of thrombin to stop bleeding is not very great and the thrombin, being liquid, runs away from the site that is damaged and needs repairing. The second type of needle therapy which is directed to treatment of cancer or tumor tissues consists of directly injecting an anti-cancer agent through a needle into the target tissue. Since the needle currently used in this techniuqe is as fine as 19G to 23G, the only anti-cancer agent that can be inejcted is antibiotics and other drugs in solution. But if the anti-cancer agent in solution is injected through the needle, it immediately departs from the target tissue and the purpose of topical application of the drug is not achieved. Therefore, it has long been desired to develop a therapeutic preparation that can be injected through a very fine needle (19-23G) into the target tissue and the area around the injection pathway and which stays at the injected site as long as it slowly releases the active agent.